This invention relates to motor vehicle safety systems, and is designed to provide an early warning of deceleration and braking in order to reduce rear end collisions.
The prior art is dominated by the use of two condition switches gauging accelerator position. Many of these switches are mechanically attached to the accelerator pedal. Possible pedal jamming and the dubious value of lighting a green light on the rear end of a car makes most of these systems unsafe (restarting a stalled car in traffic would display a green light). Many prior art systems are wired into the standard brake lights in one way or another, an obvious mistake since a short circuit would disable the brake lights.
U.S. Pat. 3,708,782 issued to Mori uses a complex decision circuit to gauge the speed at which the brake pedal is depressed. Mori's system is wired into the stock brake lights which introduces unreliability. Also this design fails to give a signal warning in a developing emergency. Often, upon seeing trouble ahead, a driver will drag his brakes in anticipation of heavy braking. Within microseconds, Mori's RC time constant decision circuit disables any emergency signal warning.